Scientists warn that the El Niño weather phenomenon is likely to be particularly intense this year, potentially becoming a 'super' El Niño. This natural event, which occurs when Pacific sea surface temperatures rise 0.5C above normal for several months, is forecast to exceed 2C later this year with a 63% probability. Such a strong El Niño would push up global temperatures and bring extreme weather to North America.
In the southern United States, wetter and stormier conditions are expected from autumn, bringing relief to drought-stricken areas but also an enhanced risk of flooding. Atmospheric rivers—giant ribbons of water vapour—could make landfall more frequently, leading to heavier rainfall and windier conditions, particularly along the west coast in winter. The jet stream's east-west orientation will allow storms to pass more quickly through the south.
Conversely, northern states and the Pacific Northwest will experience hotter and drier conditions as the jet stream shifts south. This will result in less snowfall over the northern Rockies and warmer temperatures across northern parts of the US and Canada. The Pacific Northwest will miss the storm track entirely, leading to very warm and dry weather.
The strong El Niño could also spread infectious diseases by creating favourable breeding conditions for mosquitoes and other pests. During the 2015-2016 super El Niño, outbreaks of West Nile virus, hantavirus and plague increased in parts of the US.
In the Atlantic, a quieter-than-normal hurricane season is expected between June and November due to increased wind shear, which hinders storm formation. Forecasters predict at most six hurricanes and 14 storms, compared to an average of seven hurricanes and 14 storms. Meanwhile, Pacific hurricane activity is expected to increase, mainly impacting western Mexico, with an enhanced risk for Hawaii.
Climate change is likely to increase the frequency of strong El Niño events this century, according to experts. The World Meteorological Organization warns that this year's El Niño 'will pour fuel on the fire of a warming world', exacerbating drought, heavy rainfall and heatwaves. In Canada, the impacts will arrive around the end of the year, bringing a milder winter, especially in the western half.
